1. Field of the Invention
The present invention relates to a semiconductor device and, more particularly, to such a semiconductor device using a TAB tape.
2. Description of the Related Art
There has been proposed a simply constructed semiconductor device in which a semiconductor element is mounted on inner leads of a TAB (tape automated bonding) tape and a liquid resin is molded by a potting to cover the semiconductor element. In this case, however, since the TAB tape itself is not so strong, the device as a whole may be deflected, the outer leads may float and the height of the device may become uneven. Therefore, mounting such a semiconductor device on a substrate would be inconvenient.
In recent years, therefore, there has been developed a semiconductor device in which a semiconductor element is sealed with a resin by a transfer molding step.
According to the transfer-molded semiconductor device, the outer shape is maintained by the molded portion and the device thus exhibits a strength greater than that obtained by potting and the outer leads float very little, owing to the structure.
However, since a lead of the TAB tape has a small thickness, since it is obtained by etching a copper foil, the TAB tape on which the semiconductor element is mounted and which is arranged in the metal mold causes the inner leads to be deflected due to the weight of the semiconductor element. Moreover, the semiconductor element moves in a mold cavity due to resin pressure when the resin is poured into the cavity. As shown in FIG. 17, therefore, the semiconductor element may be tilted in the sealing resin and, hence, warped and causing the height of the outer leads to become uneven.